The present paper is a continuation of my series on the New World fauna of the dacetine ant genus Strumigenys Fr. Smith. Earlier parts, containing keys to the abbreviations for measure? ments and proportions, may be found in Jour. New York Ent. Soc. 61: 53-59, 101-110 (1953). Other parts are in press. Discussed here are S. cultriger Mayr, S. deltisquama new spe? cies, and S. tococae Wheeler, considered as members of the man dibularis series. S. cultriger and S. deltisquama seem to be re? lated, and these two may be considered as members of group cultriger. They are characterized by having basic mandibularis series mandibular dentition, with the addition, on the inner or masticatory borders of each of the shafts, of a straightedged, translucent lamella which ends in a right angle just short of the proximal preapical tooth. S. cultriger shows obvious close rela? tionships to the smithii group of the mandibularis series ; S. delti? squama is somewhat more aberrant. S. tococae has mandibularis-series dentition, except that the apical fork has two, instead of only one, intercalary teeth. A rudimentary lamella is also present on the inner mandibular border, but this does not imply a close relationship to the cult? riger group; in fact, the relationships of tococae are obscure, and its assignment to the mandibularis series is tentative. Each of these three species remains known from a single col? lection at the present time, so little can be said concerning their probable distribution. S. tococae is known to inhabit plant cavities above the ground, and its very large eyes appear to rep? resent an adaptation to arboreal foraging habits.